[GitHub] [ignite-3] rpuch commented on a diff in pull request #1976: IGNITE-19269 Implemented methods to explicitly lock rows in MV storage.

["rpuch (via GitHub)" <gi...@apache.org>]

rpuch commented on code in PR #1976:
URL: https://github.com/apache/ignite-3/pull/1976#discussion_r1182249152


##########
modules/storage-api/src/main/java/org/apache/ignite/internal/storage/MvPartitionStorage.java:
##########
@@ -47,14 +48,41 @@ public interface MvPartitionStorage extends ManuallyCloseable {
     long REBALANCE_IN_PROGRESS = -1;
 
     /**
-     * Closure for executing write operations on the storage.
+     * Closure for executing write operations on the storage. All write operations, such as
+     * {@link #addWrite(RowId, BinaryRow, UUID, UUID, int)} or {@link #commitWrite(RowId, HybridTimestamp)},
+     * as well as {@link #scanVersions(RowId)}, and operations like {@link #committedGroupConfiguration(byte[])}, must be executed inside
+     * of the write closure. Also, each operation that involves modifying rows (and {@link #scanVersions(RowId)} must hold lock on
+     * corresponding row ID, by either calling {@link Locker#lock(RowId)} or calling {@link Locker#tryLock(RowId)} and checking the
+     * result.
      *
      * @param <V> Type of the result returned from the closure.
      */
     @SuppressWarnings("PublicInnerClass")
     @FunctionalInterface
     interface WriteClosure<V> {
-        V execute() throws StorageException;
+        V execute(Locker locker) throws StorageException;
+    }
+
+    /**
+     * Parameter type for {@link WriteClosure#execute(Locker)}. Used to lock row IDs before updating the data. All acquired locks are
+     * released automatically after {@code execute} call is completed.
+     */
+    @SuppressWarnings("PublicInnerClass")
+    interface Locker {
+        /**
+         * Locks passed row ID until the {@link WriteClosure#execute(Locker)} is completed.
+         *
+         * @param rowId Row ID to lock.
+         */
+        void lock(RowId rowId);
+
+        /**
+         * Tries to lock passed row ID. If successful, lock will be released when the {@link WriteClosure#execute(Locker)} is completed.
+         *
+         * @param rowId Row ID to lock.
+         * @return {@code true} if row ID has been locked successfully, or the lock has already been held by current thread.

Review Comment:
   It's about explicitness. If you think it's already obvious, ok.



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